(1) Field of Invention
The present invention relates to a series of novel silicone derivatives ot taurine. These materials are surface active silicone compounds which are useful in a personal care and related applications.
Since the compounds of the present invention are high molecular weight silicone polymers, they have a high degree of oxidative stability, even at elevated temperatures. In addition, these compounds are non volatile and non irritating to eyes and skin.
The compounds of the present invention are prepared by the reaction of an intermediate prepared by the reaction of monochloroacetic acid with a pendant hydroxyl group which is present on a silicone polymer, resulting in chloro ester which in a subsequent step is reacted with taurine. In a preferred embodiment the hydroxy containing silicone polymer has been alkoxylated with ethylene oxide, propylene oxide or mixtures thereof. The ability regulate the type of alkylene oxide and amount present in the silicone polymer results in a series of products ranging in water/oil solubility.
(2) Object of the Invention
It is the object of the present invention to provide a series of novel silicone taurine polymers, which are substantive to skin and hair. This substantivity results in superior softening, conditioning and antistatic properties. The compounds contain varying amounts of ethylene oxide and propylene oxide in the molecule. This results in the ability to vary water solubility and introduce an inverse cloud point into the molecule. Inverse cloud point is well known to those skilled in the surfactant art. It is generally found in nonionic surface active agents. It is not found in quaternary compounds. The inverse cloud point is that temperature at which a soluble compound looses it's solubility in water. Inverse cloud point, also called high cloud point, is thought to be associated with the ability of the alkylene oxide chain to hydrogen bond with the water.
It is another objective of the current invention to provide silicone taurine derivatives which are nonirritating surface active agents. The compounds of the present invention have very low irritation values when applied to skin and eyes. Irritation is a major problem with traditional surfactants.
Application of the compounds of the invention can be from solvent, aqueous dispersion or solution, or applied neat in these process. It is anticipated that the effective conditioning concentration of the compound of this invention ranges from 0.1% to 25% by weight.
The silicone polymers, suitable as raw materials, in a preferred embodiment, contain varying amounts of ethylene oxide, propylene oxide or mixtures thereof. The presence of the oxide in the silicone polymer results in compounds with an inverse cloud point. Inverse cloud point phenomenon are well known to those skilled in the art of nonionic surface active agents. The inverse cloud point is defined as a temperature above which the polymer has minimal solubility in water. If heat is applied to an aqueous solution of the nonionic at the inverse cloud point the material will become insoluble, and the solution will turn milky. It is at this point that the polymer has minimal water solubility. Since the product is no longer in solution at the above this temperature, it is within this temperature range that the product has a maximum substantivity to a fiber. The ability to use temperature to deposit a lubricant, antistat onto a fiber offers a great advantage in cost effectiveness of fiber treatment, and results in less product usage.
(3) Description of the Arts and Practices
Silicone oils (polydimethylsiloxane) have been known to be active at the surface of plastic, cellulosic and synthetic fibers as well as paper. Despite the fact that they are lubricants that are stable to oxidation, their high cost and lack of durability has made them cost prohibitive in most application areas. Silicone oils need to be emulsified prior to application. This required high pressure equipment, surface active agents and generally results in a milky emulsion. Emulsions have experienced stability problems both in terms of freeze thaw instability and upon heating. This has resulted in minimal acceptance of them in commercial products.
The low efficiency of silicone oils is due to the fact that the oil is very water insoluble. Emulsions are generally prepared which contain silicone dispersed in micelles. While this method of application is easier for processing, much of the oil stays in the surfactant micelle and never gets deposited on the fiber. That which does deposit on the fiber surface remains there by hydrophobic binding, not ionic bonding. Since the polydimethylsiloxane is not bonded the effect is very transient. The product is removed with one washing.
Taurine derivatives are known to those skilled in the art. Taurine conforms to the following structure: EQU R--N--(CH.sub.2).sub.2 --SO3 M
wherein R is alkyl, and M is a metal ion preferably an alkali metal such as sodium, potassium, ammonium or lithium.
The silicone chloro intermediate useful in the preparation of the compounds of the present invention are disclosed in U.S. Pat. No. 5,166,297 to O'Lenick, Jr. issued Nov. 24, 1992, which incorporated herein by reference.
None of the above incorporate silicone into compound. Consequently, the unique softening and substantivity properties achieved using the compounds of the present invention are not realized with the above technologies.